fix(xcat-core): site.ntpbackend is not documented anywhere

makentp reads site.ntpbackend to select the NTP daemon, and setupntp takes the same value as
--backend, but no help text names the attribute. An admin who needs ntpd on a host that has
chrony has no way to find out the attribute exists. site.dhcpbackend, which selects the DHCP
implementation the same way, is documented in the site table help.

The site table description in xCAT::Schema now carries ntpbackend beside ntpservers, with its
valid values and the auto default. The makentp man page lists it with the other site attributes
the command honors, and names the setupntp --backend option that carries the value to the nodes.

ntp_backend_selection.t reads the site help from the loaded schema and the makentp pod. Five
assertions fail without this change.

Signed-off-by: Daniel Hilst <392820+dhilst@users.noreply.github.com>

docs/source/guides/admin-guides/references/man1/makentp.1.rst

@@ -32,6 +32,8 @@ By default, it sets up the NTP server for xCAT management node. If \ **-a**\  fl
 
 \ *site.ntpservers*\  -- the NTP servers for the service node and compute node to sync with. The keyword <xcatmaster> means that the node's NTP server is the node that is managing it (either its service node or the management node).
 
+\ *site.ntpbackend*\  -- the NTP daemon to configure. Valid values are auto, chrony, and ntpd. The default is auto, which selects chrony on distributions that ship it and ntpd on older ones such as EL6 and SLES 12. If the selected daemon is not installed, \ **makentp**\  uses the other one and reports the change. The same value reaches the service nodes and the compute nodes, which the \ *setupntp*\  postscript also accepts as \ **-**\ **-backend chrony|ntpd**\ .
+
 To setup NTP on the compute node, add \ *setupntp*\  postscript to the \ *postscripts*\  table and run \ **updatenode node -P setupntp**\  command.
 
 

perl-xCAT/xCAT/Schema.pm

@@ -1283,6 +1283,11 @@ passed as argument rather than by table value',
 "              give stable output. You can increase the timeout value by specifying \n" .
 "              '--min-rtt-timeout 1s'. xCAT will append the options defined here to \n" .
 "              the nmap command.\n\n" .
+" ntpbackend:  The NTP daemon used by makentp and the setupntp postscript. Valid\n" .
+"              values are auto, chrony, and ntpd. The default is auto. In auto\n" .
+"              mode, xCAT uses chrony on distributions that ship it and ntpd on\n" .
+"              older ones such as EL6 and SLES 12. If the selected daemon is not\n" .
+"              installed, xCAT uses the other one and reports the change.\n\n" .
 " ntpservers:  A comma delimited list of NTP servers for the service node and\n" .
 "              the compute node to sync with. The keyword <xcatmaster> means that\n" .
 "              the node's NTP server is the node that is managing it\n" .

xCAT-client/pods/man1/makentp.1.pod

@@ -26,6 +26,8 @@ I<site.extntpservers> -- the NTP servers for the management node to sync with. I
 
 I<site.ntpservers> -- the NTP servers for the service node and compute node to sync with. The keyword <xcatmaster> means that the node's NTP server is the node that is managing it (either its service node or the management node).
 
+I<site.ntpbackend> -- the NTP daemon to configure. Valid values are auto, chrony, and ntpd. The default is auto, which selects chrony on distributions that ship it and ntpd on older ones such as EL6 and SLES 12. If the selected daemon is not installed, B<makentp> uses the other one and reports the change. The same value reaches the service nodes and the compute nodes, which the I<setupntp> postscript also accepts as B<--backend chrony|ntpd>.
+
 =back
 
 To setup NTP on the compute node, add I<setupntp> postscript to the I<postscripts> table and run B<updatenode node -P setupntp> command.